Multiple zeolite catalyst and method of using the same for toluene disproportionation

Abstract

The multiple zeolite catalyst is a catalytic composition used to convert alkylaromatic hydrocarbons to BTX, particularly to commercially valuable xylenes. The catalyst is formed by mixing at least two zeolites selected from mordenite, beta zeolite, ZSM-5, ZSM-11, ZSM-12, ZSM-22, ZSM-23, MFI topology zeolite, NES topology zeolite, EU-1, MAPO-36, SAPO-5, SAPO-11, SAPO-34, and SAPO-41, and adding at least one metal component selected from Group VI of the Periodic Table of the Elements. The two zeolites have different physical and chemical characteristics, such as pore size and acidity. An exemplary catalyst includes mordenite, ZSM-5, and 3 wt % molybdenum. The multiple zeolite catalyst may further be used to convert toluene to mixed xylene isomers, particularly with a ZSM-5:mordenite ratio of 2:1 by weight.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application is a continuation-in-part of U.S. patent application Ser. No. 12 / 219,927, filed on Jul. 30, 2008, and of U.S. patent application Ser. No. 13 / 353,085, filed Jan. 18, 2012, which is a continuation of the Ser. No. 12 / 219,927 application.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to catalysts used in petroleum refining, and particularly to a multiple zeolite catalyst and a method of using the same for toluene disproportionation.[0004]2. Description of the Related Art[0005]Aromatic hydrocarbons are the building blocks for many industrially important products. They are generally produced in a petrochemical complex. There are several commercial processes producing aromatics, especially xylene isomers, using a variety of reactions. Xylene isomers, including para-xylene, meta-xylene and ortho-xylene, are important intermediates, which find wide and varied application in chemical sy...

AI Technical Summary

Benefits of technology

[0019]The multiple zeolite catalyst may be used to perform toluene disproportionation, i.e., converting toluene into xylenes. The multiple zeolite catalyst contacts a toluene stream to perform the disproportionation. The disproportionation reaction preferably occurs at a temperature between approximately 200° C. and approximately 500° C. (more preferably, about 275° C. to 350° C., a pressure between 10-30 bar, and at a liquid hourly space velocity between approximately 1.0 hr−1 and approximately 5.0 hr−1 (more preferably, between 1.5 and 3.0 hr−1, and the toluene stream preferably has a hydrogen to hydrocarbon ratio of about 2:1. The multiple zeolite catalyst acts as a solid acid catalyst in the toluene disproportionation reaction, thus producing toluene conversion and higher xylene yields at lower temperatures than in conventional toluene disproportionation processes.

[0020]These and other features of the present invention will become readily apparent upon further review of the following specification and drawings.

Problems solved by technology

However, as the number of such supports and elements attests, none have been found entirely satisfactory.

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